A non-linear damage rheological constitutive model and its application to a giant slow-moving landslide
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摘要: 滑坡形成是一个典型的岩土变形破坏时效过程，低速滑坡时效过程尤为显著。基于流变理论，建立反映滑坡变形破坏发展过程的本构模型、预测滑坡活动趋势，一直是国内外滑坡研究的基本途径和难点问题之一。然而，目前国内外已有的多数流变模型仅能反映滑坡岩土蠕变的第一、第二阶段，不能刻画滑坡岩土蠕变的第三阶段（加速蠕变阶段）。本文基于滑带在滑坡中的作用以及滑带岩土剪切蠕变发展的累进性和非线性特征，借助损伤理论，在FLAC3D内置的CVISC流变本构模型中引入非线性损伤黏塑性元件，构建了可描述滑坡加速蠕变过程的非线性损伤流变本构模型，依据类比原理建立了改进的CVISC三维差分模型，通过FLAC3D开放的用户接口实现了本构模型的二次开发，并将改进的CVISC模型用于长期缓慢滑移、伴随间歇性剧烈活动的甘肃舟曲泄流坡数值模拟中。模拟结果显示，该模型不仅呈现了滑坡的加速蠕变特征，而且揭示的滑坡活动特征与其曾经出现的活动特征基本一致，从而证实基于非线性损伤理论的改进CVISC模型具有较好的有效性。
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关键词:
- 低速滑坡 /
- 滑带土 /
- 加速蠕变 /
- 非线性损伤流变本构模型
Abstract: Generation of a landslide is a typical aging process of rock and soil deformation. Therefore, it is a basic method and also a difficult problem to build constitutive models that reflect the deformation process of landslides and furthermore to use the models for prediction. However, many classical rheological models can only be used to describe the first and second creeping stages and are unable to describe the third accelerated stage. Base on the non-linear and aging characteristics of the slip zone soil during the shear creeping development and the damage theory, this paper attempts to construct a non-linear damage rheological constitutive model by combining a non-linear damage visco-plastic element with the CVISC rheological model built-in FLAC3D, namely the modified CVISC model. For implementing this modified CIVSC model in 3D numerical simulations, its 3D difference equations are developed. The numerical codes for the difference equations are programmed following the roles of the FLAC3D’s user interface program. This model is applied to simulation of the Xieliupo landslide, which is a long-term slow-moving landslide with intermittently intense movement. The results show that the modified CVISC model can disclose accelerated creeping of the landslide, which is roughly consistent with the movement history of the landslide. This gives an indication of the validity of the modified CVISC model based on non-linear damage theory. -
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